March 24: School Work starts
April 2: School Work update

Across the last 23 days of this Covid-19 Lockdown I’ve made 526 changesets, almost all updating schools & colleges in the NG UK-postcode area. I’ve been working my way down the osm.mathmos.net website page for NG from top to bottom, and am about ⅔ of the way down. The last entries added were 11 campuses for Nottingham College. This diary entry is an attempt to synthesise the intelligence gathered so far.

The definitive list of schools, etc is maintained by the UK government & published at School Information Service. Each school is given a unique URN. The OSM reference to relate to this is https://wiki.openstreetmap.org/wiki/Tag:ref:edubase=URN-Number.

Where you see the word “School” below it also refers inter-changeably to “Colleges” or “Universities”.

1. Use a Roundabout to Align the Imagery

We have a number of different imagery available to use, but all of them both need to be aligned to the ground truth & every time the map location is changed each may need to be re-aligned. The simplest & best way that I have found to do this is to zoom in on a mini-roundabout, and to align the Offset to that roundabout.

The overview is like this:
Satellite view & GPS coordinates need to be aligned to each other based on a vast array of factors: eg angle of view, ground height above sea-level, GPS coordinate system, etc.. It is made more difficult because individual tiles may come from a large range of dates and/or satellites. It would also be wonderful if all of that had been pre-processed between the native image & production of tile-to-view, but we are beggars & not the paymasters & are lucky to have any imagery to use at all. Fortunately, we Brits are obsessed with roundabouts and there is always one close to where we are mapping. Further, OS street-mapping from the government has been imported for all Britain.

Here is the process step-by-step:-

1. Select on the screen something already mapped at the place that you are about to map
2. Make sure that Continuous download (Alt+Shift+F1) is switched OFF
3. Press the ‘-‘ key & examine the local roads until you find a mini-roundabout
4. Zoom in until it is central & very close in the screen
5. Switch Continuous download ON
6. If badly offset, right-click on the active Imagery Layer & choose Offset|New offset
   (Use Tab key to switch the Dialogues panel ON if OFF)
7. Centre the mini-roundabout within the road network on screen
8. Press Okay when satisfied
   (give it a name if you wish)
9. Press the ‘3’ key
   (you will be back at the place to map)

2. OSM expects a School/College/University to be a closed Way

This is placed on the perimeter of the school Cadastre (the land-parcel that defines the school); it is a series of linked nodes. School buildings, roads, paths, playgrounds, fields, parking, etc. can then be defined within the Cadastre.

3. Multi-site Schools should be placed within a MultiPolygon Relation

Each Campus should have it’s own closed Way just like a single-site school as above; it helps a lot to give unique https://wiki.openstreetmap.org/wiki/Tag:name=campus-name for each Cadastre. Then each campus should be added to a multi-polygon relation.

The obvious type of Relation would seem to be type=site, but even that wiki page says to use Multipolygon for schools.

How-To-Map Instructions are in the earlier Diary entry.

Simple buildings can be placed into a Multipolygon, but complex buildings with holes cannot. This is because a simple building is just a specialised closed-Way, but a complex building is another Multipolygon and they are explicitly forbidden. It is best to just use a school Cadastre as Members.

Try not to use Relations as members within the MultiPolygon, I have found some schools where a Cadastre has been defined using a relation composed of pre-existing lengths of other ways. That is a legal way of defining a Cadastre, but is a bummer if the school is multi-campus. Little Geo-software is likely to be able to handle multi-depth Relations, anymore than most humans can.

4. The Amenity goes on the Cadastre or the Relation

For simple schools with a single-site, the https://wiki.openstreetmap.org/wiki/Tag:amenity=school/college/university is placed on the Cadastre, as are Address, Contact & ref:edubase.

For multi-campus schools, Address & Contact are normally placed on the Cadastre, but everything else goes into the relation Tags.

5. The osm.mathmos.net page for NG will be unusable until it updates

I’ve been spending my time converting many Relations to closed Ways, and some closed Ways to Areas-within-Relations, so many of the links will be inoperative until the page updates.

Well, at least I’m using my time usefully.

19 April: Postscript

Now complete after 26 days at 582 schools updated in the NG Postcode area, with possibly an additional 200 or 300 (up to 900 total) updates on previously-updated schools/colleges. Those extra updates were due to having learnt more about the whole process and that, of course, is what the above is about, to try to cement that learning within myself & pass it on to others.

NG is at better than 96% coverage. I’m now going to tackle the SG postcode (my grandchildren live in Ware), which is only 50% covered.

Thoughts on the whole process:
• There was just one NG-postcode school that was using a www.school web-address for their website (I did not even know that ‘school’ was a TLD!)
• I cannot tell you the number of school websites that I had to hunt through their sitemap to find the Contacts page-link
• The number of websites that forgot to add their School name to the Contact Address
• There were school websites that showed only a blank page — and nothing else — if JavaScript was switched OFF. Then the websites whose menus were inoperative without JavaScript ON. Those with JavaScript-obscured email addresses so effective that Chromium could not interpret it. Hey! Schools! The 1990s has called: it wants it’s JavaScript back.

EduBase Thoughts

I’ve been attacked (yet again, but more on that in a future Diary entry) for my reliance on the UK Government site that makes use of EduBase stats.

In brief, and largely as educated guesses, the site draws from a govt-supplied set of stats on UK Schools and makes the raw info available, searchable & cross-referenced. It is damn useful.

Like all such compilations it is subject to data-entry error, and it has been forceably pointed out to me (quite rightly) that the stats need cross-checking. The art of teaching your grandmother how to suck eggs comes to mind (I’ve been dealing with databases since the 1980s). Nevertheless the site does sometimes give pause for thought when the postal county address for Long Eaton is given for different schools variably as Nottinghamshire & Derbyshire (I’m told that it is Derbyshire). In the end, find the Contacts page for the school & get that info from there.

As far as licensing (a hot OSM issue) each page includes:

All content is available under the Open Government Licence v3.0, except where otherwise stated

OGL v3.0 generally is fine whilst the Wiki says “Datasets should be reviewed on a case-by-case basis”. I’ve not personally seen anything yet that gives me pause (ianal).

School Operator

This one is problematic in the best of circumstances.

EduBase does not have an Operator field, whereas the JOSM School preset does (there is sometimes information within an EduBase Proprietor field). If the school has an Academy / Trust field then that is likely the Operator. If not an Independent school, then the Local authority field is a likely one. One way is to check the website or email addresses. As a recent example, I’m dealing with the following:

• Amwell View School
• Website: https://amwell.herts.sch.uk/
• Email: [email protected]

You will notice that both the website & email addresses are “herts.sch.uk”, which is a sure sign that this school is operated by the local County Council (Hertfordshire).

Finally, we meet the Independent / VA (“Voluntary Aided”) sector of UK schools. Good luck with those! Hopefully there will be information within the website but it is not (as I understand it) a statutory requirement.

Leave Operator blank if unsure.

Onwards & upwards.